Fixing Corrupted Encrypted Flash Content

I've installed flash v11.7.700.202 on a Windows 7 (Ultimate) x64 box with plenty of disk, RAM, etc. The CPUx are idle.

This is a problem with Firefox v20+ (e.g. 20.1, 21) and Flash v11+

Firefox v18.x & Flash v10.8 worked.

Amazon instant video works with IE v10 & Flash v11.7, the encrypted video link below, IE only provides a download option, not an inline execution ability (downloaded video works fine using a DivX player).

I've also installed v11.7 from the offline installer (after first uninstalling the online installer version) from:

http://helpx.adobe.com/flash-player/kb/installation-problems-flash-pla yer-windows.html#main-pars_header

Received message is that I've installed successfully (from install_flashplayer11x32_mssd_aih.exe)

Troubleshooting, I see that I've install successfully from Adobe's site:

http://helpx.adobe.com/flash-player.html

I can play UN-encrypted video from:

http://drmtest2.adobe.com/Content/Unencrypted/

I cannot play encrypted video (from Amazon) or from Adobe:

http://drmtest2.adobe.com/Content/FAXS4/Anonymous_LOCAL/sample.mp4

No Event Log warnings or errors were made.

How does one go about debugging this problem or should I just use Silverlight?